This invention relates to derivatives of imidazolidin-2-ones and -2-thiones of the formula I ##SPC2##
and to their acid addition salts with pharmacologically acceptable acids, in which R.sup.1 is hydrogen or lower alkyl; R.sup.2 is lower alkyl, nitrothiazolyl, or nitrofuryl; or R.sup.1 and R.sup.2 together with the nitrogen to which they are attached are a heterocyclic group containing 4-6 carbon atoms, or 4 carbon atoms and an additional nitrogen atom which may optionally be substituted with a lower alkyl group, or 4 carbon atoms and an oxygen atom, for example a piperidino, azepino, N.sup.4 -methylpiperazino, or a morpholino group; R.sup.3 is hydrogen or lower alkyl; R.sup.4 is lower alkyl or aralkyl, for example benzyl or .alpha.-methylbenzyl; or R.sup.3 and R.sup.4 together with the carbon atom 5 of the imidazolidine ring to which they are attached are a carbocyclic ring containing 5-6 carbon atoms attached in spiro fashion to said imidazolidine ring; R.sup.5 is lower alkyl or cycloalkyl containing from 5-6 carbon atoms; and X is an oxygen or a sulfur atom. The compounds of this invention possess positive inotropic activity and are useful as cardiac stimulants, especially in the treatment of cardiac insufficiency, of shock, and of conditions associated with low cardiac output.
Compounds which may be considered as being somewhat related to the compounds of this invention of formula I, but which differ principally in having R.sup.1 representing an acyl group, such as the formyl, benzoyl, or benzenesulfonyl group, with R.sup.2 being hydrogen, have been described by I. Ugi in Angew. Chemie, Int. Ed., Vol. 1, p. 8 (1962), in particular pp. 18-19, and by Ugi et al. in Liebig's Ann. Chem. Vol. 666, p. 54 (1963). However, those latter compounds differ significantly from the compounds of this invention is possessing a non-basic, essentially neutral acylamino (amide) function attached to position 1 of the imidazolidine ring, while the compounds of this invention have in that same position a secondary or tertiary substituted amino group or a nitrogen-containing heterocyclic group attached to position 1 through its tertiary nitrogen atom. The fundamental differences in chemical and physical properties between an acylamino (amide) function, such as present in position 1 of the compounds described by Ugi et al., and a secondary or tertiary amino function as present in position 1 of the compounds of this invention are well known and fully recognized in the art. For example, the acylamino (amide) function is essentially neutral, while in contradistinction thereto the secondary or tertiary amino group in position 1 of the compounds of this invention is basic in nature. Moreover, the compounds described by Ugi et al., do not possess the pharmacological properties of the compounds of this invention, nor is there any suggestion to be found in the literature that they might perhaps possess cardiac stimulating activities.